Method for manufacturing glass from the gas phase

Abstract

A method for the manufacture of starting materials for fiber optical waveguides and the like from gas phase, wherein glass compositions are produced in a reaction zone in the presence of condensation nuclei being additionally introduced into said reaction zone and being used to increase the rate of glassforming and the rate of deposition of said glass composition being deposited on a solid surface as a soot or a powder. The nuclei can be added as particles of micron size to a carrier or reaction gas that is to be introduced into the reaction zone. The particles can be themselves produced immediately before the deposition zone in a reaction gas mixture which is subsequently introduced into the reaction zone.

What we claimed as our invention: 
     
       1. A method for manufacturing glass by means of deposition from the vapor phase which comprises feeding reaction gases into a vapor phase reaction zone, said reaction gases being capable of reacting to form a glass-forming chemical compound in a chemical reaction, the conditions in said reaction zone being sufficient to initiate said chemical reaction and cause particles of said glass-forming chemical compound to deposit out of said reaction zone onto a solid surface in a deposition zone as soot, fusing said soot to form a glass film, feeding into said reaction zone micron-sized particles of said glass-forming chemical compound while said chemical reaction is occurring in said reacton zone, said particles acting as condensation nuclei, and being present in sufficient amount such that the rate of formation of said soot and the rate of its vapor phase deposition on said solid surface is increased. 
     
     
       2. A method according to claim 1, wherein said condensation nuclei are introduced into said reaction zone in form of a least one pulverulent oxide. 
     
     
       3. A method according to claim 2, wherein said oxide is silica. 
     
     
       4. A method according to claim 2, wherein said oxide is an oxide of a dopant for said glass composition, which is to be deposited. 
     
     
       5. A method according to claim 1 which comprises withdrawing an aerosol of undeposited particles produced by said chemical reaction from said reaction zone, and recirculating said aerosol back into said reaction zone. 
     
     
       6. A method according to claim 1, which includes the step of admixing said condensation nuclei with at least one of said reaction gases entering said reaction zone. 
     
     
       7. A method according to claim 1, which includes the step of admixing said condensation nuclei with a carrier gas, which is introduced into said reaction zone. 
     
     
       8. A method according to claim 1, wherein said condensation nuclei are chemically produced during said chemical reaction in a zone outside said reaction zone and are introduced from said zone into said reaction zone. 
     
     
       9. A method according to claim 8, wherein said condensation nuclei are chemically produced in at least one of said reaction gases and are introduced together with said one reaction gas into said reaction zone. 
     
     
       10. A method according to claim 9, including the steps of: preheating said mixture of reaction gases in a preheating zone to a temperature less than the temperature existing in said reaction zone to initiate partially said chemical reaction to form particles of said glass composition suspended in said mixture, and introducing said mixture together with said particles suspended in said mixture into said reaction zone and after said chemical reaction in said reaction zone into said deposition zone.